Voltage regulators, for example DC-DC converters, supply a stable power source to an electronic system. Voltage regulators are typically designed to maintain terminal voltage sources within specified limits even in variable input voltage and/or load conditions. Voltage regulators are typically susceptible to faults or failures, which can cause the output voltage of the regulator to go outside a suitable range during a fault. A fault in the voltage regulator can damage a device using the regulated DC voltage or render the device unusable.
A fault may not be detected until the affected voltage regulator is out of tolerance as determined by a fault detection device that monitors the output voltage of the regulator. To avoid catastrophic failure of the system, redundant voltage regulators can be used to ensure reliability, coupled in parallel to a load device so that if one voltage regulator fails, another continues to maintain a stable supply voltage.
In a system with a redundant power source configuration such as a 2N or N+1 configuration, over-voltage protection methods typically involve monitoring of the associated power rail to determine an upper voltage limit of correct operation. Action can be taken, usually in hardware, to protect sensitive circuitry on the power rail in the event that the monitored voltage rail exceeds the upper limit by removing power to the rail. As a result of the fault, the entire system may shut down to protect the sensitive circuitry.
Conventional multiple-supply systems determine over-voltage by simply monitoring one or more output voltages. With one voltage, the source of the error in a multi-sourced power system cannot be determined. Over-voltage conditions can progress very quickly. As a result, the most sensitive supply shuts down first, followed almost instantly by the remaining supplies with the faulty supply which detects the error is also shut down. The system is protected but all power to the load is lost.